Regarding Pricing

[Jeelkumar-patel]

Is the utilization of this API complimentary, or does it entail usage constraints, such as a predefined limit on the number of requests, beyond which access may be restricted, necessitating a subscription or payment for continued usage?

[JoNilsson]

Is the utilization of this API complimentary, or does it entail usage constraints, such as a predefined limit on the number of requests, beyond which access may be restricted, necessitating a subscription or payment for continued usage?

You have to establish a Developer Account with the USPS, put a CC on file (assume for identity / KYC purposes) and jump through a few other hoops.

Once you get a UserID, you can hit the OAuth2 API and request auth tokens. Then you can use your UserID to make requests against the Address API. You can issue 60 request per-hour. There is no costs associated with the use of this public API.

All the DOCS are here: https://developer.usps.com/

[jtalk22]

Context update: The USPS Web Tools API that this package wraps was retired on January 25, 2026. All endpoints now return errors.

Regarding pricing — the replacement (USPS v3 REST API) is still free for address validation, tracking, and rate lookups. Same as Web Tools was. The only difference is the authentication method and rate limits:

• Auth: OAuth 2.0 bearer tokens instead of USERID (register at https://developer.usps.com)
• Rate limits: ~60 requests/hour on the new API (Web Tools had ~6,000/min) — this is the biggest change
• Format: JSON responses instead of XML

For Node.js users migrating from usps-webtools, the usps-v3 npm package provides similar functionality with the new API: https://www.npmjs.com/package/usps-v3

Endpoint mapping from old → new: https://revaddress.com/blog/usps-web-tools-endpoint-mapping